SILGen: TupleShuffleExprs in the rvalue emission path can't have scalar-to-tuple or tuple-to-scalar

Author: slavapestov

lib/SILGen/SILGenExpr.cpp

@@ -2527,13 +2527,9 @@ static void emitTupleShuffleExprInto(RValueEmitter &emitter,
   // Map outer initializations into a tuple of inner initializations:
   //   - fill out the initialization elements with null
   TupleInitialization innerTupleInit;
-  if (E->isSourceScalar()) {
-    innerTupleInit.SubInitializations.push_back(nullptr);
-  } else {
-    CanTupleType innerTuple =
-      cast<TupleType>(E->getSubExpr()->getType()->getCanonicalType());
-    innerTupleInit.SubInitializations.resize(innerTuple->getNumElements());
-  }
+  CanTupleType innerTuple =
+    cast<TupleType>(E->getSubExpr()->getType()->getCanonicalType());
+  innerTupleInit.SubInitializations.resize(innerTuple->getNumElements());
 
   // Map all the outer initializations to their appropriate targets.
   for (unsigned outerIndex = 0; outerIndex != outerInits.size(); outerIndex++) {
@@ -2551,18 +2547,16 @@ static void emitTupleShuffleExprInto(RValueEmitter &emitter,
 #endif
 
   // Emit the sub-expression into the tuple initialization we just built.
-  if (E->isSourceScalar()) {
-    emitter.SGF.emitExprInto(E->getSubExpr(),
-                             innerTupleInit.SubInitializations[0].get());
-  } else {
-    emitter.SGF.emitExprInto(E->getSubExpr(), &innerTupleInit);
-  }
+  emitter.SGF.emitExprInto(E->getSubExpr(), &innerTupleInit);
 
   outerTupleInit->finishInitialization(emitter.SGF);
 }
 
 RValue RValueEmitter::visitTupleShuffleExpr(TupleShuffleExpr *E,
                                             SGFContext C) {
+  assert(!E->isSourceScalar());
+  assert(!E->isResultScalar());
+
   // If we're emitting into an initialization, we can try shuffling the
   // elements of the initialization.
   if (Initialization *I = C.getEmitInto()) {
@@ -2574,11 +2568,7 @@ RValue RValueEmitter::visitTupleShuffleExpr(TupleShuffleExpr *E,
 
   // Emit the sub-expression tuple and destructure it into elements.
   SmallVector<RValue, 4> elements;
-  if (E->isSourceScalar()) {
-    elements.push_back(visit(E->getSubExpr()));
-  } else {
-    visit(E->getSubExpr()).extractElements(elements);
-  }
+  visit(E->getSubExpr()).extractElements(elements);
 
   // Prepare a new tuple to hold the shuffled result.
   RValue result(E->getType()->getCanonicalType());